Add test for secret-define/undefine

```
  NAME
    secret-define - define or modify a secret from an XML file

  SYNOPSIS
    secret-define <file>

  DESCRIPTION
    Define or modify a secret.

  OPTIONS
    [--file] <string>  file containing secret attributes in XML


  NAME
    secret-undefine - undefine a secret

  SYNOPSIS
    secret-undefine <secret>

  DESCRIPTION
    Undefine a secret.

  OPTIONS
    [--secret] <string>  secret UUID

```